How to Restring a String Trimmer (Bump-Feed and Fixed-Line Heads)

Restringing a trimmer head is quick once you've done it — a couple of minutes, no tools beyond scissors for most heads. The confusing part is that the steps depend entirely on which head type you have, and that's rarely obvious once the original packaging is long gone.

This covers the three common head styles — bump-feed, fixed-line (manual wind), and pre-wound universal spools — plus the jamming and uneven-feed problems that usually mean something was wound wrong rather than a broken trimmer.

What you'll need

Replacement line in the diameter and shape your trimmer's manual calls for — using the wrong diameter is the most common reason a freshly restrung head won't feed correctly. See our string trimmer line size guide if you're not sure what your trimmer takes.

Beyond the line itself, most heads only need scissors or a utility knife to cut line to length. Keep needle-nose pliers nearby in case old, brittle line has snapped off flush and needs to be picked out of the eyelets.

Restringing a bump-feed head

Bump-feed heads hold a spool inside the housing that feeds a bit more line each time you tap the head on the ground. To reload, remove the housing cap (usually by pressing in two side tabs or twisting, depending on the model), lift out the empty spool, and note which direction the old line was wound — most spools have small arrows molded into the plastic.

Feed each end of the new line through the eyelets on the housing before dropping the spool back in, then wind each piece onto the spool in the marked direction, leaving a few inches sticking out through the eyelets. Seat the spool, check that the spring (if your head has one) sits correctly underneath it, and snap the cap back on.

Winding line in the wrong direction is the single most common bump-feed mistake — it causes the spool to tighten against itself instead of releasing line when you bump it, which looks identical to a jammed or broken feed mechanism.

Restringing a fixed-line (manual-wind) head

Fixed-line heads have two short pieces of line loaded directly into the head rather than a wound spool, and you replace them by hand each time they wear down or snap short. Pull out what's left of the old pieces, then cut two new lengths to the size specified in your manual — typically enough that each piece extends to roughly the trimmer's cutting width once both ends are out.

Thread each new piece through its mounting hole or clip until it's held securely, usually by a barb, knot, or small retaining clip built into the head. There's no winding involved, which is why fixed-line heads are popular on lighter-duty trimmers — reloading takes seconds, at the cost of needing a reload sooner since there's no reserve of extra line stored inside.

Loading a pre-wound universal spool

Some bump-feed heads accept pre-wound replacement spools instead of bulk line, which skips the winding step entirely — pop the cap, drop in the new spool with the line ends threaded through the eyelets, and close it back up.

Universal spools are sized to fit a given head diameter, not a specific brand, but they're not interchangeable across every trimmer. Double-check the spool is rated for your head before buying a multi-pack, since a spool that's slightly the wrong diameter can sit loose or bind inside the housing.

Why line jams or won't feed out after restringing

If line won't release when you bump the head, the most likely cause is winding direction — unwind and redo it following the arrows molded into the spool or housing. Overlapping wraps are the second most common cause; line needs to sit in even, side-by-side layers, not crossed over itself, or it will bind as it unwinds.

If the head feeds unevenly with one side shorter than the other, the spool's two line ends likely came loose and tangled together inside the housing during winding. Pull the spool back out, unwind a few turns, and rewind that section with both lines kept separate and taut.

Cracked or chewed-up eyelets are a different problem that restringing won't fix — line will keep fraying or snapping right at the eyelet no matter how it's wound. Replacement eyelets or a new head are inexpensive fixes; if the trimmer itself is old enough that parts are getting hard to find, it may be time to look at a replacement instead.

When it's worth replacing the trimmer instead

A trimmer that needs frequent restringing because of a worn-out feed mechanism, a cracked housing, or a motor that's lost power is usually not worth the repair cost once it's several seasons old. Our best cordless string trimmers roundup covers current picks across bump-feed and fixed-line designs if you're at that point.